Soil nail/micropile comprising dissimilar bars connected with transition coupler

ABSTRACT

A soil nail or micropile comprises a first steel bar having a first end, a second end and a non-threaded exterior surface, a second steel bar having a first end, a second end, and an exterior surface which is threaded at the second end, and a transition coupler joining the second end of the first steel bar to the first end of the second steel bar, whereby when installed in-ground, the first steel bar is located in the ground and the second threaded end of the second steel bar protrudes from a surface of the ground, such as for accepting a bearing plate and threaded nut.

RELATED APPLICATION DATA

The present application claims priority to U.S. Provisional Application Ser. No. 63/194,325, filed May 28, 2021, which application is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to methods and devices used for ground reinforcement.

BACKGROUND OF THE INVENTION

Soil nails and micropiles are steel bars that are placed inside of a drilled hole that is filled with grout. They provide passive reinforcement in the soil and require a nut to be threaded on the end of the nail/micropile to hold a bearing plate against the soil or structural surface (usually shotcrete) in the case of a soil nail and hold a bearing plate in a concrete slab/footing in the case of a micropile. Soil nails are typically used in an inclined horizontal application for earth retention and micropiles are generally used in a vertical or battered vertical application for foundation support. Typical industry practice is to use a continuously threaded bar or rod (with either hot rolled, cold rolled or cut threads) or to alternatively thread the end of a piece of rebar.

The problem with using a continuously threaded bar or rod is that this is more costly as the cost for the threading is applied across the entire bar when it is only needed at the end of the bar.

A problem with using threaded rebar is that the threading of the rebar typically reduces the cross sectional area of the bar and therefore the strength requiring the bar to be “upsized” and more expensive. Also, a longer than typical thread is needed (usually 8″ to 1 foot) to allow for variability in installation.

SUMMARY OF THE INVENTION

Embodiments of the invention comprise a soil nail/micropile and methods of assembling or installing a soil nail/micropile. In embodiment, a soil nail/micropile comprises rods or bars that are connected to one another, such as via a transition coupler. In one embodiment, a transition coupler is used to connect two dissimilar bars or rods, such as having dissimilar exterior patterns.

In one embodiment, a soil nail or micropile comprises a first steel bar having a first end, a second end and a non-threaded exterior surface, a second steel bar having a first end, a second end, and an exterior surface which is threaded at the second end, and a transition coupler joining the second end of the first steel bar to the first end of the second steel bar, whereby when installed in-ground, the first steel bar is located in the ground and the second threaded end of the second steel bar protrudes from a surface of the ground, such as for accepting a bearing plate and threaded nut.

In one embodiment, the first steel bar comprises rebar.

In one embodiment, the exterior surface of the second steel bar is threaded from the first end to the second end.

In one embodiment, a length of the first steel bar exceeds a length of the second steel bar.

In one embodiment, the transition coupler has a first aperture at a first end for accepting the second end of the first steel bar and a second aperture at a second end for accepting the first end of the second steel bar.

The transition coupler may align the first steel bar and the second steel bar in a longitudinal direction.

In one embodiment, a corrosion protection element may be located over at least a portion of the soil nail or micropile.

Further objects, features, and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a soil nail in accordance with the present invention;

FIGS. 2-4 illustrate embodiments of a soil nail including secondary corrosion protection in accordance with the invention; and

FIGS. 5-8 illustrate embodiments of a micropile both with and without secondary corrosion protection and in vertical and battered orientation in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth in order to provide a more thorough description of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the invention.

Embodiments of the invention comprise a soil nail/micropile and methods of assembling or installing a soil nail/micropile. In embodiment, a soil nail/micropile comprises rods or bars that are connected to one another, such as via a transition coupler. In one embodiment, a transition coupler is used to connect two dissimilar bars or rods, such as having dissimilar exterior patterns.

Referring to FIG. 1 , in one embodiment, a soil nail 20 comprises a first rod or bar 22, a second rod or bar 24, and a transition coupler 26 which joins the first rod or bar 22 and the second rod or bar 24.

The first rod or bar 22 has a first end and a second end. In one embodiment, the first rod or bar 22 has first characteristics, such as comprising a non-threaded rod or bar which may have one or more first surface characteristics. As one example, the first rod or bar 22 may comprise steel rebar having one or more irregular surface features.

The soil nail 20 also comprises a second rod or bar 24. The second rod or bar 24 has a first end and second end. The first end is, as described below, preferably coupled or joined to the second end of the first rod or bar 22. The second rod or bar 24 preferably has second surface characteristics. The second characteristics are preferably different than the first characteristics of the first rod or bar 22. In one configuration, the second characteristics comprise threads.

In this regard, in a preferred configuration, the exterior surface of the first rod or bar 22 is not threaded. However, one or more portions of the second rod or bar 24 are preferably (unlike the first rod or bar 22) externally threaded. In one configuration, only portions of the second rod or bar 24 may be threaded, such as just the second end or just the first and second ends. However, in a preferred configuration, the entire second rod or bar 24 is threaded. This configuration provides the greatest flexibility in installation (where, as described below, one or more nuts may need to be threaded onto the bar and along a sufficient distance thereof to engage a bearing plate.

In one embodiment, the soil nail 20 further comprises a transition coupler 26. The transition coupler 26 is configured to engage the second end of the first rod or bar 22 and the first end of the second rod or bar 24. The transition coupler 26 may thus comprise a body having a first means for connecting, engaging or accepting the second end of the first rod or bar 22, such as at a first end of the transition coupler 26, and a second means for connecting, engaging, or accepting the first end of the second rod or bar 24. The first and second means may be the same or may be different. The first and second means may comprise one or more of an aperture for accepting an end of the rod or bar and/or one or more fasteners for joining the coupler to the rod or bar. For example, the transition coupler 26 might have one or more of the following configurations or features:

Cold-swaged steel coupling sleeve;

Cold-swaged coupler with taper-threaded ends;

Coupler for thread-like deformed reinforcing bars;

Extruded steel coupler with parallel threaded ends;

Friction-welded bar coupler with parallel threads;

Friction-welded coupler with taper-threaded ends;

Grout-filled coupling sleeve;

Grout-filled coupling sleeve with parallel thread at upset bar ends;

Grout-filled coupling sleeve with taper thread;

Shear screw and rail coupling sleeve;

Shear screw and wedge coupling sleeve;

Steel-filled coupling sleeve;

Taper-threaded steel coupler;

Threaded coupler with standard national coarse threads;

Threaded coupler with upsized bar threads, cold forged;

Threaded coupler with upsized bar threads, hot forged;

Upset bar and coupling sleeve with straight threads; and

Coupling sleeve.

In one configuration, where the first rod or bar 22 and the second rod or bar 24 are linear, the transition coupler 26 preferably aligns them longitudinally.

Additional aspects of the soil nail 20 will be appreciated from a description of the use thereof, such as a method of installing or placing the soil nail 20. In one embodiment, the first rod or bar 22 is placed in a drilled hole H inside ground G which is to be stabilized. The first end of the first rod or bar 22 is located at the terminus of the drilled hole H or in the ground G beyond the terminus of the drilled hole. The second end of the first rod or bar 22 is located towards a surface of the ground G.

The soil nail 20 is positioned so that the second end of the second rod or bar 24 extends from the drilled hole H (and the ground G). As illustrated, grout, such as concrete, may be located around the soil nail 20 inside of the drilled hole H. Further, a stabilizer, such as shotcrete, may be located at the surface of the ground G around the drilled hole H. The second end of the second rod or bar 24 preferably extends there beyond. A bearing plate 30 may be located on the second end of the second bar or rod 24 and at least one nut 32 may be threaded onto the second end of the second bar or rod 24 against the bearing plate 30.

In one embodiment, the first rod or bar 22 may be connected to the second rod or bar 24 by the transition coupler 26 prior to placement in the ground. In other embodiments, the second rod or bar 24 might be connected to the first rod or bar 22 after it has been placed in the drilled hole H.

As illustrated, the transition coupler 26 may generally be located near the external terminus of the soil nail 20, thus allowing the second bar or rod 24 to be generally short (such as shorter than the first rod or bar 22). This allows the length of the more expensive second rod or bar 24 (such as due to threading) to be reduced, thus reducing cost.

In FIGS. 1-4 , the soil nail 20 is illustrated as used in a generally horizontal application. It will be appreciated that the soil nail 20 might be used vertically or generally vertically (e.g. as a “micropile”), such as illustrated in FIGS. 5-8 .

In the configuration illustrated in the figures the soil nail 20 is used in tension. However, the soil nail 20 might be used in compression, such as when used in the form of a micropile (wherein the transition coupler 26 might have a different configuration than when it is used in a tensile application, given that the coupler 26 then only needs to transmit the compressive load from the second rod or bar 24 to the first rod or bar 22).

FIG. 1 illustrates an application of a “bare” soil nail 20, such as where the bars or rods 22, 24 are bare or have an epoxy coating. As illustrated in FIGS. 2-4 , one or more portions of the soil nail 20 may be located inside/behind an optional corrosion protection element, which may be referred to as Double Corrosion Protection (DCP). The DPC may comprise a element or a material which is placed over or around at least a portion of the soil nail 20 to provide additional corrosion protection. As illustrated in FIG. 2 , the DCP may be located over just the portion of the second rod or bar 22 between the transition coupler 26 and the bearing plate 30. As illustrated in FIG. 3 , the DCP may further extend over or around the transition coupler 26, and as illustrated in FIG. 4 , the DCP may yet further extend over or around the first rod or bar 22.

As indicated, the first and second rods or bars of the soil nail may have a variety of configurations. In one embodiment, they may be generally circular in cross-section. However, all or parts thereof might have other cross-sectional shapes.

It will be understood that the above described arrangements of apparatus and the method there from are merely illustrative of applications of the principles of this invention and many other embodiments and modifications may be made without departing from the spirit and scope of the invention as defined in the claims. 

What is claimed is:
 1. A soil nail or micropile comprising: a first steel bar having a first end, a second end and a non-threaded exterior surface; a second steel bar having a first end, a second end, and an exterior surface which is threaded at said second end; and a transition coupler joining said second end of said first steel bar to said first end of said second steel bar; whereby when installed in-ground, said first steel bar is located in the ground and said second threaded end of said second steel bar protrudes from a surface of said ground for accepting a threaded nut.
 2. The soil nail or micropile in accordance with claim 1, wherein the first steel bar comprises rebar.
 3. The soil nail or micropile in accordance with claim 1, wherein said exterior surface of said second steel bar is threaded from said first end to said second end.
 4. The soil nail or micropile in accordance with claim 1, wherein a length of said first steel bar exceeds a length of said second steel bar.
 5. The soil nail or micropile in accordance with claim 1, wherein said transition coupler has a first aperture at a first end for accepting said second end of said first steel bar and a second aperture at a second end for accepting said first end of said second steel bar.
 6. The soil nail or micropile in accordance with claim 1, wherein said first steel bar and said second steel bar are aligned in a longitudinal direction by said transition coupler.
 7. The soil nail or micropile in accordance with claim 1, further comprising a corrosion protection element located over at least a portion thereof.
 8. A method of utilizing a soil nail or micropile comprising: forming an aperture from a ground surface into the ground therebelow; locating a soil nail or micropile comprising a first steel bar connected to a second steel bar with a transition coupler and having a first end and a second end, said second end bearing threads on an exterior surface thereof, so that said first end thereof, said first steel bar and said transition coupler are located in said aperture, and so that said second end thereof extends outwardly of said ground surface; locating a bearing plate on said second end; and threading a nut onto said threaded second end of said soil nail or micropile.
 9. The method in accordance with claim 8, further comprising locating grout in said aperture around said soil nail or micropile.
 10. The method in accordance with claim 8, further comprising locating a stabilizer around said second end of said soil nail or micropile.
 11. The method in accordance with claim 8, further comprising locating an optional corrosion protection element over at least a portion of said soil nail or micropile located in said aperture.
 12. The method in accordance with claim 8, wherein said first steel bar comprises rebar having an unthreaded exterior surface.
 13. The method in accordance with claim 8, wherein said first steel bar is longer than said second steel bar.
 14. The method in accordance with claim 8, wherein said aperture is generally vertically extending. 